Electric motors are a significant source of radiated and conducted electromagnetic emissions, referred to herein as electromagnetic disturbance (EMD), which can degrade the performance of a device, equipment, or system. EMD can be radiated and conducted through electrical lines from sources such as the motor, electronic devices, and the like. Controlling conducted and radiated emissions produced by different electrical and electronic devices, including electric motors, is critical for protecting electronic equipment in the surrounding environment.
Many electric motor assemblies include EMD suppression components such as capacitors and inductors mounted within the motor itself. However, as packaging space becomes more limited, it has become increasingly difficult to package these components within the motor housing. Moreover, as electromagnetic interference (EMI) requirements are becoming more strict, improved EMD suppression is required.
EMD suppression chip devices have been developed to mitigate some of the problems of the prior art. An EMD suppression chip device is a generally rectangular prism element that can be located inside the motor housing and is capable of suppressing noise generated by the electric motors. An EMD suppression chip device has two input terminals, respectively connectable to the two motor terminals, and at least one earth terminal electrically connectable to a conductive ground path.
A problem associated with the incorporation of an EMD suppression chip device into a motor assembly is that of securing the EMD suppression chip device, especially in a high vibration environment. For example, when the motor assembly is in a vehicle, the motion and vibration of the vehicle can cause the EMD suppression chip device to move or vibrate out of contact with one or both motor terminals and/or the ground path. Of course, should the EMD suppression chip device become disconnected from the motor terminals and/or the ground path, its ability to suppress noise generated by the motor is severely compromised. Thus, what is needed is a motor assembly incorporating a securely positioned EMD suppression chip device for electromagnetic disturbance suppression.